An MgZnO-based thin film has attracted attention as a semiconductor material for use in a semiconductor light emitting device, a high-speed electronic device, a surface acoustic wave device and the like. Note that, in the following description, a term “MgZnO-based” is a concept including MgZnO or ZnO.
In the case of using the MgZnO-based thin film as the semiconductor material, a variety of problems have occurred. As one of major problems, mentioned is that it has been difficult to convert the MgZnO thin film into p-type.
In this connection, in recent years, as seen in Non-Patent Document 1 and Non-Patent Document 2, research on a technology for converting the MgZnO thin film into the p-type and on the semiconductor light emitting device using such a p-type MgZnO thin film has been made. However, the p-type MgZnO thin films described in these documents are each formed on such a special substrate as a ScAlMgO4 substrate, and accordingly, it is difficult to achieve mass production and cost reduction thereof, and it is difficult to make the MgZnO thin films into commercial products.
Here, it is considered to use a substrate made of an MgZnO-based semiconductor as a substrate for forming the p-type MgZnO thin film thereon. The substrate made of the MgZnO-based semiconductor is more easily available than the above-mentioned substrate, and accordingly, it is considered that industrial applicability of the p-type MgZnO thin film can be enhanced.
[Non-Patent Document 1] A. Tsukazaki et al., Japanese Journal of Applied Physics, Vol. 44, No. 21 (2005), pp. L643-L645
[Non-Patent Document 2] A. Tsukazaki et al., Nature Materials, Vol. 4 (2005), p. 42